Association Between Serum Level of Hepatitis B Surface Antigen at End of Entecavir Therapy and Risk of Relapse in E Antigen–Negative Patients

Background & Aims This study investigated whether serum level of hepatitis B surface antigen (HBsAg) at the end of entecavir treatment was associated with risk of relapse. Methods We performed a prospective multicenter study of 161 consecutive patients with chronic hepatitis B in whom the hepatitis B virus was no longer detected after 3 years or more of entecavir therapy. Treatment ended between July 1, 2011 and July 1, 2015. Patients were monitored for clinical relapse (hepatitis B virus DNA >2000 IU/mL and level of alanine aminotransferase more than 2-fold the upper limit of normal) and virologic relapse (hepatitis B virus DNA >2000 IU/mL). Outcomes were calculated using the Kaplan-Meier method and risk factors were identified by Cox proportional hazards modeling. Results Two years after therapy ended, 49.2% of patients in the entire cohort had a clinical relapse (95% confidence interval [CI], 40.9%–58.1%) and 81.7% had a virologic relapse (95% CI, 74.3%–88.0%). Among patients who were hepatitis B e antigen–negative at the end of therapy, 39.2% had a clinical relapse (95% CI, 30.3%–49.6%) and 77.4% had a virologic relapse (95% CI, 68.6%–85.2%). Serum level of HBsAg was associated with relapse in the hepatitis B e antigen–negative patients (P_trend = .006 for clinical relapse; P_trend = .0001 for virologic relapse). In multivariate Cox regression analysis, the hazard ratio (per log IU/mL increment) for clinical relapse was 2.47 (95% CI, 1.45–4.23) and for virologic relapse was 1.80 (95% CI, 1.33–2.45). The 11 (9%) patients with levels of HBsAg <10 IU/mL did not relapse. Conclusions Serum level of HBsAg is associated with risk of relapse in patients who are hepatitis B e antigen–negative after treatment with entecavir. A low titer of HBsAg might be used to identify patients at low risk for relapse after treatment.